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| Titel |
Measurements of halogen oxides in the Western Pacific |
| VerfasserIn |
Folkard Wittrock, Hannah Walker, Dwayne Heard, Trevor Ingham, Johannes Lampel, Martin Horbanski, Katja Grossmann, Astrid Bracher, Justin Sentian, Mihalis Vrekoussis, Ru-Jin Huang, Enno Peters, Anja Schönhardt, Andreas Richter, John P. Burrows |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250082777
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| Zusammenfassung |
| Reactive halogens such as iodine, bromine and their oxides have received growing attention
in the past years owing to their strong impact on tropospheric composition. In particular,
reactive halogens deplete ozone and alter the HOx and NOx ratios, consequently changing
the oxidizing capacity of the troposphere. The halogen oxides iodine monoxide
(IO) and bromine monoxide (BrO), generated from the reaction of atomic I and Br
with ozone, play a central role in these processes. Iodine atoms may be released by
photolysis of precursor substances such as I2 or volatile iodocarbons emitted from
the marine biosphere. Inorganic release processes are also being considered, but
they are so far uncertain. Bromine precursors include organic as well as inorganic
sources.
Here we report on measurements of IO and BrO during and related to the SHIVA field
campaign, which has been carried out in November 2011 in the Western Pacific around
Borneo. Different techniques have been applied in order to detect the trace gases:
cavity-enhanced differential optical absorption spectroscopy (CE-DOAS), multi axis
(MAX)-DOAS, airborne multi axis (AMAX)-DOAS and laser induced fluorescence
(LIF, discussed in detail in Heard et al.). While for BrO no clear signal above the
detection limit was found, IO levels up to 2.5 ppt were found in the open Sulu Sea and
similar levels up to 2 ppt close to seaweed farms around Semporna, Malaysia. In this
area both MAX-DOAS and AMAX-DOAS observations gave indication for the
presence of uplifted layers of IO. These results are discussed and interpreted by
using complementary observations of the main precursor substances. In addition
correlation studies taking into account meteorological and oceanic parameters have
been carried out to identify possible source processes. Finally the ground-based IO
observations have been compared to satellite observations and a reasonable agreement was
found. |
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